Regulatory and access status
Hibsago 150 mg prefilled syringe, containing bepirovirsen sodium, was formally approved in Japan on 24 August 2026, listed for reimbursement on 14 October, and launched in October. This was the first regulatory approval of bepirovirsen worldwide.
Restricted eligible population
The label is for adults with persistent HBV infection who have received nucleos(t)ide analogue therapy for at least six months, have baseline HBsAg at or below 3,000 IU/mL and HBV DNA below 90 IU/mL, and do not have cirrhosis.
Phase III endpoint and denominators
The primary endpoint was functional cure at week 72, maintained for 24 weeks after all treatment stopped. B-Well 1 reported 127/650 (19.5%) versus 0/328; B-Well 2 reported 106/570 (18.6%) versus 0/286. The pooled analysis was 233/1,220 (19%) versus 0/614. These selected non-cirrhotic adults do not represent all people with hepatitis B.
Functional cure is not viral eradication
Functional cure means that HBV DNA and HBsAg remain undetectable in blood for at least 24 weeks after all treatment is stopped. It does not prove complete elimination of intrahepatic viral genetic material.
Do not stop NA therapy independently
Hibsago is given with nucleos(t)ide analogue therapy for 24 weeks. NA therapy continues for a further 24 weeks, after which discontinuation may be considered by a specialist only if specified virological and biochemical criteria are met.
Key risks
Important risks include liver injury with ALT elevation, serious inflammatory or immune-related events, and thrombocytopenia. Specialist monitoring is required.